1. Field of the Invention
This invention relates to the formation of titanium nitride electrical conductors in semiconductor devices and, more specifically, to the chemical vapor deposition of such titanium nitride conductors.
2. Brief Description of the Prior Art
Titanium nitride is an electrically conductive material which is generally used in semiconductor fabrication as a nucleating layer or for local interconnects. Titanium nitride films for use in the fabrication of semiconductor devices have generally been provided in the past in cold wall chemical vapor deposition (CVD) reactors by reacting titanium tetrachloride with ammonia and hydrogen according to the reaction: 2 TiCl4+2 NH3+H2.fwdarw.2TiN+8 HCl. TiN has also been produced with the hydrogen omitted. However, it has been necessary to operate at temperatures generally above 500 degrees C. and usually at even higher temperatures in order to obtain a high TiN deposition rate. The deposition rate is a critical factor, especially in a single wafer reactor. It is known that deposition temperatures above about 500 degrees C. and sometimes as low as 400 degrees C. will cause ultimate device degradation if, for example, the semiconductor device being fabricated already has aluminum thereon or if the transistors have already been formed in or on the substrate.
It is also known that a silicon film has been shown deposited in situ before and/or after the TiN for gate application as set forth in U.S. Pat. No. 4,570,328 of Price et al.
It is therefore apparent that a TiN deposition process which deposits TiN at a rate on the order presently obtained by prior art relatively high temperature procedures and which can be operated at temperatures of about 400 degrees C. and even lower is highly desirable and has been long sought by the art.